setting default proxy port from system property differs fromJDK standard

related to / can be clubbed with #1793

## Describe the bug
As per JDK documentation of [networking properties](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/doc-files/net-properties.html), if `http.proxyPort` is not set the default port (`80` for http, `443` for https) will be taken.

However the [AWS sdk implementation](https://github.com/aws/aws-sdk-java-v2/blob/16b1f5719bb8966c99c37236a203f8d873f5e586/http-clients/apache-client/src/main/java/software/amazon/awssdk/http/apache/ProxyConfiguration.java#L200) is setting the default to be zero `0`.

PS: current implementation doesn't honor https variants (`https.proxy*`) also.